Generally sorption machines (including adsorption and absorption machines) that are working intermittently use a two-steps process. In the first step the reactor of the sorption machine is heated, this is referred to as the charging step. In the second step, the reactor of the sorption machine is cooled, this is referred to as the discharging step. If the sorption machines consists of multiple unites it is necessary to have good thermal connections to each, also considering a possible temperature difference between different heat sources. A sorption machine (i.e. a chemical heat pump) generally comprises a reactor. In order to bring about good performance to the sorption machine it is essential that the energy delivery, to and from, the reactor of the sorption machine can be obtained without hindrance. For this reason, it is important to have a good thermal contact and conductivity between the media transferring energy to the reactor during heating and the media transporting energy from the reactor during cooling. This is normally achieved by having several valves, pumps and pipes redirecting the transfer media from the reactor of the sorption machine to either a hot or a cool source. This activity consumes parasitic energy and requires investments in piping causing costs. Instead of using pumps, valves and pipes it is also well known that heat pipes can be used for both heating and cooling purposes.
If heat pipes are used in the above mentioned setup it has to be at least two heat pipes both of them in good and permanent contact with the reactor. One heat pipe should be for cooling and the other on should be for heating. Generally, heat pipes work continuously without any possibility to interrupt the process. However, this is not feasible in the above setup since both heat pipes in this case will be constantly working against each other, resulting in a situation where the heat received to the reactor by one of the heat pipes, will then at the same time be taken away by the other heat pipe.
Heat pipes where the heat transfer can be regulated solve this problem. It is also necessary to have extended energy uptake from the thermal transistor. Solutions with heat pipes which can be controlled have been disclosed.
JP59-138895 discloses a switchable heat pipe where the transfer of heat is controlled by a magnetic body movable within the heat pipe. The magnetic body changes the volume of a space where the working fluid of the heat pipe can be stored. When the working fluid is in the storage space it does not participate in heat transfer. The magnetic body is controlled by a magnet and is moving up or down in the space to change the volume.
Problems in the prior art include that a force which is not negligible has to be used to control the moving body. Thus it is desirable to reduce the force and energy which has to be used to control a switchable heat pipe.
Another problem in the prior art is that the disclosed solution is most suitable for a heat pipe which only has to be switched on and off. A continuous regulation of the heat transfer capacity of heat pipe would be difficult using the approach disclosed in the prior art. Thus it is a problem how to provide a heat pipe where the usable volume of the working fluid can be changed continuously to the desired volume.
A further problem in the prior art is that the construction does not easily allow a heat pipe which can be manufactured in different sizes at an industrial scale.
Yet another problem in the prior art is that several heat sources with different temperatures or slightly different temperatures cannot easily be connected to the same heat pipe.